Yes I was a bit hasty in that thinking DUH oops. BUT the same is true with hot lights.
The way it actually works is as follows: A leaf shutter opens and closes from the centre; i.e. the centre of the shutter opens first and closes last. This helps to actually reduce vignetting by giving preferential exposure to central rays passing through the lens and partially obscuring the outer rays. That's just like stopping down the aperture iris. The net result is that at larger apertures and higher shutter speeds the exposure is slightly less than it should be all over the frame, but vignetting is actually reduced.
Q: Does stopping the iris down increase vignetting?
A: No, it does not!
Q: Can a leaf shutter therefore possibly increase vignetting?
A: No, it cannot!
Q: Are you making up spurious "facts" to support your argument?
The way it actually works is as follows: A leaf shutter opens and closes from the centre; i.e. the centre of the shutter opens first and closes last. This helps to actually reduce vignetting by giving preferential exposure to central rays passing through the lens and partially obscuring the outer rays. That's just like stopping down the aperture iris. The net result is that at larger apertures and higher shutter speeds the exposure is slightly less than it should be all over the frame, but vignetting is actually reduced.
Q: Does stopping the iris down increase vignetting?
A: No, it does not!
Q: Can a leaf shutter therefore possibly increase vignetting?
A: No, it cannot!
Q: Are you making up spurious "facts" to support your argument?
A: Yes, you are!
On Tue, Apr 1, 2014 at 5:52 PM, James Schenken <jds@xxxxxxxxxxxxxxx> wrote:
Randy,Could you clarify the following comment you made?"I just did a test with my Rodenstock 90mm f6.8 and the difference from f8 and f45 is about a 1/10 of a stop difference. ... Or maybe my Elenchrom power packs aren't accurate but I did get the same exact reading with 5 pops at each aperture. "It sounds as if you did the testing with electronic flash and not hot lights.Is that so?JamesSmall typos corrected.
CPAP Therapy is a way to live.
